Re: [PATCH RFC v4 0/6] iio: add Open Sensor Fusion IIO driver

[Kim Jinseob]

> Other than the fact that new revisions must not be sent as a diff on top
> of a prior revision, please stop sending new versions without actually
> replying to my v1 comments.

You are right, sorry for the noise.

I made a process mistake here. I prepared v4 on top of the previously sent
series instead of preparing it as a full standalone replacement series from
the proper base. I will not ask you to review v4 in that form, and I will
prepare the next revision as a full series from a clean base.

I also should have answered your protocol versioning questions directly before
sending another revision.

> What does "v0" mean here? Is the data format not complete yet?
> Are versions of the protocol likely to be backwards compatible?
> Will the device identify what version of the protocol it implements?

The current OSF wire header starts with a fixed 4-byte magic, "OSF0", at a
fixed offset. The same header also carries explicit protocol_major and
protocol_minor fields at fixed offsets.

For the currently supported firmware and driver, protocol_major is 0. The "0"
in "OSF0" is intended to denote the current major wire-format revision, not
the Linux driver identity.

The binding is intended for devices implementing this discoverable OSF header
layout. The driver currently supports protocol major version 0. Minor version
changes are intended to be backward compatible. Incompatible wire-format
changes require a new protocol_major value.

If a future major revision cannot be discovered using the same fixed header
layout, or is not compatible with this binding, it should use a new compatible
string.

I will spell this out in the binding commit message and documentation in the
next revision.

Jinseob